Clinical Study Of Cardiac Resynchronization Therapy In Patients With Congestive Heart Failure

Part OneThe effects of cardiac resynchronization therapy in patient with congestive heart failureBACKGROUND Cardiac resynchronization therapy(CRT),by pacing right and left ventricles,can improve symptoms and reduce mortality for heart failure patients with cardiac dyssynchrony.Among those patients,someone improve more significant and so called as CRT hyper-responders.However,nearly 1/3 patients failed to response to CRT. B-type natriuretic peptide(BNP) reflects both haemodynamic status and neurohormonal activation and could predict the prognosis of chronic heart failure.Previsualization of the cardiac venous system is very important for cardiac resynchronization therapy(CRT). The possibility of the visualization of the venous system of the heart in multidetector computed tomography(MDCT) has been documented.OBJECTIVE In addition to analysis the efficacy and complications of CRT implantation,we aim to evaluate the value of NT-pro-BNP in predicting the clinical response to CRT and the role of MDCT in the implantation of left ventricular lead. METHODS The study included 56patients with chronic heart failure due to ischemic or dilated cardiomyopathy.They were studied with conventional and tissue Doppler imaging days before implantation.After being proved to be with cardiac dyssynchrony, patients were implanted with CRT.Then,plasma levels of NT-proBNP was evaluated before and 3 months after implantation.Clinical,echocardiographic and exercise parameters were monitored at each clinic visit after CRT implantation. The anatomy of the CS and its tributaries was studied using MDCT scans in 14 patients (5men;age 59±9 years).RESULTS All 56 patients were proved to be with cardiac dyssynchrony.The baseline mean left ventricular ejection fraction(LVEF) was 29.7±6.8%,left ventricular diastolic diameter was 75.2±10.5mm.Complications included four case of failing to cannulate coronary sinus and two case of arrhythmia.After a mean 18.9±16.0 months of follow-up,11 patients were identified as CRT non-responders and 3 patients were identified as CRT hyper-responders.CRT resulted in a significant reduction in NT-pro-BNP(1697.8±1279.8 vs.1074.97±874.6 fmol/ml,p＜0.001) in responders. Percentage change in NT-pro-BNP level(△BNP%) was a powerful predictor of long-term clinical improvement at 3 months of follow-up.In 70%of the patients,it was possible to obtain similar images to those during the CRT implantation procedure within left anterior oblique view.The coronary sinus was clearly visible in all cases,the ostium measured 14.5±2.5 mm.CONCLUSIONS It was feasible and safe to pace left ventricle through coronary sinus although with some procedure-related complications.CRT contributes to improvements of cardiac function and synchronicity.NT-pro-BNP may be a simple method for monitoring the effects of CRT.The anatomy of the CS and its tributaries can be evaluated using MDCT.MDCT can be useful in techniques where previsualization of the cardiac venous system is recommended. Part TwoComparing Analysis of The Optimal AV/PV and VV Delay between An IEGM-based and Echocardiogram for Cardiac Resynchronization Therapy in Heart Failure PatientsBackground Nearly 30%of patients failed to response to cardiac resynchronization therapy(CRT).To decrease the occurrence of nonresponders,besides a careful selection of patients referred for CRT,clinical evidences support the importance of an optimization of the atrioventricular(AV) and interventricular(VV) delays.Intracardiac delay optimization of biventricular and dual-chamber pacing devices currently relies on time-consuming echocardiographic measurements.A novel intracardiac electrogram (IEGM) method for atrioventricular(AV/PV) and interventricular(VV) delay optimization was developed,which can be performed during routine device follow-up. Methods and Results In this prospective,nonrandomized,multi-center trial,patients previously implanted with St.Jude Medical CRT devices underwent standard AV/PV and/or VV delay optimization guided by Doppler echocardiogram measurements of the maximum aortic velocity time integral(aortic VTI).Aortic VTI measurements applying the IEGM method recommended delays were then obtained in all patients.Nine patients (age:59±6 years;67%male;11%ischemic) were enrolled for AV/PV and VV delay evaluation.An independent core lab determined the maximum aortic VTIs.Data analysis of the AV,PV,and VV delays demonstrated the concordance correlation coefficient (CCC) between the standard method aortic VTI values and the IEGM method aortic VTI values was 97.8%,98.5%,and 99.3%,respectively.All analyses demonstrated that the CCC＞90%(P＜0.001).Conclusion The automated programmer-based IEGM method provides a reliable and simpler alternative to standard techniques for the optimization of AV/PV and VV delay settings in patients with CRT-D devices and dual-chamber ICDs. Part ThreeThe Effects of Cardiac Resynchronization Therapy on the electrophysiological characteristics of HeartBackground Previous clinical trials for cardiac resynchronization therapy(CRT) were conducted under the condition of simultaneous LV-RV pacing.This mode of pacing is safe,yet not effective in preventing sudden cardiac death.So far,no study has been done to examine the effect of CRT with LV-RV timing offset on inducibility of ventricular arrhythmias.In addition,the benefits of CRT on atrial function and atrial reverse remodeling have been demonstrated,but its impact on electrophysiolo- gical property of atria has not been fully evaluated.Objective To investigate the the effect of CRT with LV-RV timing offset on inducibility of ventricular arrhythmias and the effects of CRT on atrial conduction abnormalities as estimated by P-wave maximum duration(PWM) and P-wave dispersion(PWD) in advanced heart failure patients.Methods and Results--We conducted electrophysiology study in 9 patients who underwent CRT implant under three pacing conditions:RV pacing,LV-RV simultaneous pacing and CRT with LV-RV timing offsets at 0 ms,+50 ms,+80ms,-50ms,and -80ms (+means LV ahead of RV and - means RV ahead of LV).Up to two extra-stimuli were introduced through RV or LV lead.The mean age of the patients was 64±5 and mean EF was 30%±6%.40%of patients had ischemic cardiomyopathy and 60%had nonischemic cardiomyopathy.Five patients(56%) had either VF(1 patients) or more than 10 beats of non-sustained MMVT(2 patients) and non-sustained PMVT(2 patients).The difference in patients with inducible VT/VF between CRT with and without LV-RV timing offset was statistically significant(50%versus12%,P＜0.01).In addition,Thirty-six patients (27 men,9 women,mean age 58 +/- 10 years) with CRT pacemakers were enrolled in this study.PWM and PWD were measured using 12-lead surface electrocardiography (ECG) at a paper speed of 50 mm/s and 20mm/mV.Serial ECGs,echocardiography and clinical assessment were performed at baseline and 3 months after CRT.At the end of the 3 months,PWM and PWD values were significantly decreased(for PWM:from 134.4±9.2 to 124.2±10.2 ms,P＜0.0001;for PWD:from 43.6±8.2 to 31.3±10.7 ms; P＜0.0001).It noted a decreased trend of left atrial diameter between the follow-up time and the baseline(from 46.4 +/- 5.4 to 44.8+/- 6.1 mm,P = 0.0613).Conelusions CRT with LV-RV timing offset may potentiate the inducibility of ventricular arrhythmias in patients with advanced heart failure.Long-term studies are needed to correlate the findings from the programmed electrical stimulation and the spontaneous ventricular arrhythmias and to examine the potential detrimental effect of LV-RV timing offsets on electric stability of the heart.CRT is associated with a decreased duration of PWM and PWD and this may reflect a reduction in the probability of atrial fibrillation in heart failure patients.